孤岛交直流混合微电网群分层协调控制

针对孤岛运行的交直流混合微电网群提出分层协调控制策略。首先设计分布式发电单元(DPDG)与储能单元底层控制,自适应调节交流子网频率与直流子网电压,保证各交、直流子网的独立稳定运行。同时考虑到直流子网中恒功率负荷(CPL)的影响,进一步对各DPDG单元设计P-V~2改进下垂控制,减小传统下垂控制产生的直流母线电压偏差。进而考虑各储能单元充放电能力不同,设计基于荷电状态(SOC)的动态一致均衡控制,确保储能子网协调优化运行。然后基于直流子网电压和交流子网频率信号,构造功率自治级、功率互济级和储能平衡级三级控制切换策略,实现子网间功率互助并减少系统的功率损耗。最后基于Matlab/Simulink搭建了混合微电网群仿真模型对所提控制策略进行了验证。

Hierarchical coordinated control of island AC/DC hybrid microgrids

A hierarchical coordinated control strategy is proposed for island AC/DC hybrid microgrids. First, the underlying control of a Dispatched Distributed Generation (DPDG) unit and an energy storage unit is designed to adjust the frequency of an AC subgrid and the voltage of a DC subgrid and ensure the independent and stable operation of both subgrids. At the same time, considering the influence of the Constant Power Load (CPL) on the DC subgrid, an improved droop control using P-V2 is designed to reduce the voltage deviation caused by traditional droop control. Considering the different charge or discharge capacity of each energy storage unit, the dynamic consistent equilibrium control strategy based on SOC is constructed to ensure the optimal operation of the storage subgrid. Based on the DC subgrid voltage and the AC subgrid frequency signals, it constructs a three-level control switching strategy of power autonomous level, power mutual aid level and energy storage balance level, so as to realize power mutual assistance among subgrids effectively and minimize the power loss of the system. Finally, a hybrid microgrid simulation model is built through Matlab/Simulink to verify the proposed control strategy. This work is supported by the National Natural Science Foundation of China (No. 61873159), Shanghai Science and Technology Commission (No. 18020500700), Shanghai Engineering Research Center of Green Energy Grid-Connected Technology (No. 13DZ2251900) and "Electrical Engineering" Shanghai Key Laboratory of Power Station Automation Technology of Class II Plateau Discipline.